1. Field of the Invention
The present invention relates to the processing of a substrate such as the sputtering, etching, deposition, or other processes. More particularly, the present invention provides a method and an apparatus in and by which the processing of the surface of a semiconductor wafer or a substrate (which will be simply referred to as "substrate" hereafter) can proceed under an optimally controlled environment.
2. Description of the Prior Art
The conventional processing of the surface of a substrate such as any of the sputtering, etching, depositing, and other processes must usually be carried out by accurately controlling the temperature of the substrate during the sputtering process, etc., since the results from the sputtering process, etc. may depend largely upon the temperature of the substrate being processed.
One of the preferred approaches that addresses the problem of measuring the actual temperature of a substrate during the sputtering process, etc. may be to use a thermopile temperature sensor to measure the temperature in a non-contacting manner which is typical in the prior art.
The thermopile sensor includes a large number of thermocouples which are sensitive to any thermic or heat rays from the surface of a substrate being processed. This sensor provides output that represents the actual temperature value of the substrate being processed at every moment. It is noted that a substrate being processed has an inherent emissivity that may vary, depending upon the kind of material, surface conditions, and other factors. For this reason, the thermopile sensor cannot provides the accurate measurement of the actual temperature of the substrate in response to those different heat rays. In the prior art, the thermopile sensor is primarily used to measure the temperature of the surface of the substrate. When a thin film is formed during a depositing process in particular, this sensor cannot be used to measure the actual temperature of the substrate being processed. During the deposition process, therefore, it is practically impossible to monitor any abnormal or unusual change in the temperature on a real time basis.